Photographic print



All@ l5 1950 E. E. JELLEY l 2,518,695

`x Ho'1oGRm=HIc PRINT 'Filed Marh 3o, 1946 F/L'g.

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PutentedAug. 15,A 1950 4r'n'o'ro'Guarino P RINT E. Jelley, Rochester,`N. Y., assignor` to Eastman Kodak Company, Rochester, N. Y., a

y `corporation of New J ersey 'Application March 30, 1946, SerialNo.'658,513

' 3 claims. (C1. 41-22) This invention relates to photographicsupciiically the ratio of tluorine compound to vehicle portsspecifically to light-diusing supports such should be greater than 1:2.Similarly over 50% as paper or white nlm. Specifically the present ofthe dispersed particles should be smaller than invention is an improvedmodification of the in- .2 micron in diameter, preferably about .1micron ventionof Hanson and Evans described in patent 5 but actuallythere is no lower limit on the invenapplication 576,230, filed February5. 1945, now tion except ofcourse that particles of molecular abandoned.size do not constitute dispersed particles. In this The object of theinvention is to provide a low latter connection, cross reference is madeto coindex subbing layer between the picture layer and pending, nowabandoned, application Serial No. the light-diffusing support so as toeliminate l0 654,757 filed March 15, 1946, by Dr. Gale F. halationeffects in accordance with the Hanson Nadeau and the continuation-n-partapplicaand Evans invention. tion thereof. Ser. No. 73,964, led February1, It is the main object of the invention to prov1949, now Pat. No.2,481,770 of September 13, 1949, vide a subbing material which may becoated relative to solutions of soluble fluorine com- 'satisfactorilyand which is compatible both with l5 pounds, particularly for use as anantihalation the base and with the photosensitive layer or the layer infilms. Particles larger than .2 micron image layer which thephotosensitive layer ultiincrease the diffusivity of the layer making itact mately becomes. more like the paper base itself and thus the Thepresent invention is based on my discovery larger particles mightconceivably reduce the efthat the index of refraction of a layer isactually ficiency of the present invention aside from the affected bymaterials dispersed therein provided fact that they do not aid inreducing the index the particles are less than .2 microns in diameter.of refraction and hence are wasted. Particles about .1 micron are ofcourse far above The present invention is illustrated in the acmoleculardimensions and yet they do contribute companying drawing in which: tothe refractive index of the medium in which Fig. 1 is a highly magnifiedcross section of a they are dispersed. According to the invention,photosensitive material incorporating the present a subbing layer ismade up of a finely dispersed invention. iiuorlne compound such ascryolite or sodium Fig. 2 similarly illustrates a multicolor printiluosilicate dispersed in a protective film of plastic incorporating apreferred embodiment of the such as cellulose acetate or polymethylmethpresent invention.

acrylate. It is an advantage to use a protective In Fig. 1 aphotosensitive layer I0 is coated on plastic having, itself, as low arefractive index as a subbing layer II which contains a finelydispossible. The refractive index of the compo-site persed fluorinecompound in a transparent promaterial is not easy to measure since itdoes not tective plastic vehicle. This is carried by a lightgive a sharpcritical angle of internal reflection diffusing support I2 which may bepaper or white when placed on an Abbe refractometer, but neverfilm orwhichv may include a transparent layer theless, practical tests haveshown that the index next to the subbing layer II. The wavy line I3 ofrefraction is quite low and that the material is is used to indicatethat light diffusion occurs capable of giving and does give, aremarkable somewhere in the layer Il, possibly right at its diminutionin stain level when used in color surface. It is c-ommon practice totreat the surph-otographs. There is in most cases a, certain face of thepaper with successive coatings before residual degree of diifusivity inthe subbing layer coating a photosensitive layer thereon. due to thedispersed particles, but in practice this In Fig. 2, a print consistingof a multicolored too is negligible. Of course the diiiusivity wouldimage I5 is carried on a light-diffusing support at worst, act merelylike the paper base without made up of a plurality of layers. Of theselayers, the present invention, but in fact it does not de- I6 and I8 aretransparent SubbingS, I1 is a 10W tract greatly from the presentinvention regardrefractive index layer according to the present ing itsability to reduce highlight'stain. 'Ihe invention containing finelydispersed cryolite in effects ci such stain are most noticeable in colorcellulose acetate. The supporting layer I9 is photographs and hence thepresent invention is light diffusing as indicated by the wavy line 20most desirable in connection with such photoincluded therein. graphs.The low refractive index layer should be be- In order to get a usefuleffect there should be tween .00005 and .005 inch thick as taught by ahigh percentage of fluorine compound in the Hanson and Evans in order togive the optical transparent vehicle in which it is dispersed, speeseilect required. Also the index of refraction of Iclaim:

Laphotographicprintmaterlaicompthingawhitelight-diilusingbasc.anintermediatelayerbetween.00005and.005inchthickcoated0nthebaseandconsistingofanedispersionolcryoliteinawaterprotectiveil'ansparentvehicle selected from the group consisting ot celluloseesters and polyalkylmethacrylates, the ratio ofiluorinecompoundtovehiclebeinggreaterthan 1:2andover50%ofthedispersedparticlesbeingsmallerthanzmicronindiametenanda lightsensitive layer coated on the front ot the intermediate layerwithanindexof retraction at least .08 greater than that o! theintermediate layer.

2. A color photograph comprising a transpar-4 ent layer containing amulticolored picture, a llight-diilusing backing for the picture andbetween the backing and the picture layer an intermediate layer between.00005 and .005 inch thick 25 4 the ratio of iluorine compolmd tovehicle being reaterthan 1:2 andover 50% otthedispersedpeticleabeingsmallerthan3mionindiamf 3. A photographic sheet containinga trans-v parent layer, a light diffusing layer and betweenparentvehicle selected from the group consistv i118 of cellulose esters andpolyalkylmethacrylates. the ratio of cryolite to vehicle being greaterthan 1 :2 and over 50% of the dispersed particles being smaller than .2micron in diameter.

EDWIN E. JEILEY..

REFERENCES CITED The following references are of record in the le ofthis patent:

.UNITED STATES PATENTS Number Name Date 2,331,716 Nadeau et al Oct. 12,1943 2,376,428 Hansel! May 22, 1945 2,391,127 Carver Dec. 18, 19452,400,365 Murray May 14, 1946 2,400,366

Murray 1--.. May 14. 1946

1. A PHOTOGRAPHIC PRINT MATERIAL COMPRISING A WHITE LIGHT-DIFFUSINGBASE, AN INTERMEDIATE LAYER BETWEEN .0005 AND .005 INCH THICK COATED ONTHE BASE AND CONSISTING OF A FINE DISPERSION OF CRYOLITE IN A WATERPROTECTIVE TRANSPARENT VEHICLE SELECTED FROM THE GROUP CONSISTING OFCELLULOSE ESTERS AND POLYALKYLMETHACRYLATES, THE RATIO OF FLUORINECOMPOUND TO VEHICLE BEING GREATER THAN 1:2 AND OVER 50% OF THE DISPERSEDPARTICLES BEING SMALLER THAN .2 MICRON IN DIAMETER, AND A LIGHTSENSITIVE LAYER COATED ON THE FRONT OF THE INTERMEDIATE LAYER WITH ANINDEX OF REFRACTION AT LEAST .08 GREATER THAN THAT OF THE INTERMEDIATELAYER.